The United Nations’ climate chief called on the world’s richest countries to fulfill their climate financing goals, as global leaders gathered for a virtual climate summit hosted by the White House.

Speaking to Yahoo Finance, Patricia Espinosa, executive secretary of the United Nations Framework Convention on Climate Change, said the failure of developed nations to deliver on their $100 billion a year in funding commitment to poorer countries, threatens to undermine trust and confidence in the Paris Agreement.

“[International financing] has really become one of the most important elements to ensure a good outcome at COP 26,” Espinosa said, referencing the 2021 United Nations Climate Change Conference (COP 26) in Glasgow, scheduled for November. “It's not because that amount will really be an offer that is sufficient to drive the transformation, It has become something like a trust building signal, where developed countries would be sending the signal that they are actually willing to comply with the commitments that they make.”

Developed nations, including the U.S., committed to raise climate finance for vulnerable countries in 2009. The plan called for nations to increase those pledges to $100 billion by 2020. The Paris Agreement called for a higher amount to be negotiated, and take effect from 2025. Yet, more than a decade later, neither commitment has been realized.

That issue of funding has taken on increased importance as developing nations emerge from the COVID-19 pandemic shouldered with debt. Fifty-four percent of emerging economies find themselves in debt distress or at high risk of distress, according to an independent report published by the UN. That has severely hampered the governments’ ability to respond to the climate crisis, in nations most affected by extreme climate.

“Climate change is really a multiplier of every single challenge that humanity is facing,” Espinosa said. “Unfortunately, this means that in the countries that are most vulnerable, that are the poorer countries, unfortunately, really endure a lot of the costs and of the negative consequences of climate change.”

Washington has aimed to reclaim a leadership role on climate, after a four-year absence under the Trump administration, which withdrew the U.S. from the Paris Agreement.

'Climate change does not recognize any borders'

On Thursday, President Biden pledged to slash U.S. emissions by at least half of 2005 levels, by 2030, seven months ahead of the UN Conference, where nations party to the Paris Agreement are set to announce new emissions goals.